Suppose that a person riding on the top of a freight car shines a searchlight beam in the direction in which the train is traveling.

how does the speed of the light beam relative to the ground compare to the speed of beam when the train is at rest?

same

Explanation:

Acc. to Einstien's postulate of special theory of

Relativity , Velocity of the light beam is same in all frames of references

(a) If the freight car is at rest

The frame we can assumed as Non - inertial frame  of reference s

In the inertial frame of reference , velocity  of the light beam  has its own value as : 3 x 10^8 m/s

(b) If the freight car is moving , the frame we can assumed as  Non -inertial frame of reference    

In thus case also , The velocity of the light beam  will also have  the same value as ; 3 x 108 m/s

-first use of geothermal energy occurred more than 10,000 years ago in north america by american paleo-indians

-the first industrial use of geothermal energy began near pisa, italy in late 18th century

-in 1904, italian scientist piero ginori conti invented the first geothermal electric power plant in which steam was used to generate the power

-with the above experiment, the first geothermal plant in usa started in 1922 with a capacity of 250 kilowatts

-however, in 1946 first ground-source geothermal heat pump installed at commonwealth building in portland, oregon

-during the 1960’s, pacific gas and electric began operation of first large scale geothermal power plant in san francisco, producing 11 megawatts

-in 1973, when oil crisis began many countries began looking for renewable energy sources and by 1980’s geothermal heat pumps (ghp) started gaining popularity in order to reduce heating and cooling costs

-as effect of climate change started showing results, governments of various countries joined hands to fight against it, for which kyoto protocol was signed in japan in 1997, laid out emission targets for rich countries and required that they transfer funds and technology to developing countries, 184 countries have ratified it

hope this

prndulum needs thread, weight clock to time swings